1. Technical Field
The present disclosure relates to a terminal that enables an electric connection with the outside, wire connecting structure and a method of manufacturing a terminal, and particularly relates to a terminal made of copper or a copper alloy that is attached to an electric wire, a wire connecting structure and a method of manufacturing a terminal.
2. Background Art
In the field of vehicles, in view of improving fuel consumption, there is a need for lightweighting of various components constituting automobiles. Particularly, a wire harness used in automobiles is a component having a second heaviest weight next to an engine in an automobile and thus, for lightweighting, there have been efforts to change a material of a conductor (core wire) of an electric wire used in the wire harness from copper to one of aluminum and an aluminum alloy. Normally, a base material made of one of copper and a copper alloy is used for a terminal connected to a leading end portion of an aluminum or aluminum alloy wire. Accordingly, since there is a possibility that exposed aluminum produces dissimilar metal corrosion and the conductor becomes defective at a connecting portion between the conductor and the terminal that are made of the aforementioned materials, it is necessary to take measures such as to shield the aluminum conductor from the outside world.
To this end, it is known to mold an entire crimp portion with a resin (Japanese Laid-Open Patent Publication No. 2011-222243). However, this results in a bulky connector since the size of a connector housing needs to be larger because of a bulky mold portion, and thus a wire harness as a whole cannot be miniaturized or have a higher density.
With a molding method, since individual crimp portion is processed after the crimping of an electric wire, there is a problem that manufacturing processes of a wire harness may largely increase or become cumbersome.
In order to solve such a problem, there are proposed techniques such as a technique in which a metal cap is placed to cover the electric wire conductor and thereafter crimped to thereby bring an aluminum conductor into a sealed state (Japanese Laid-Open Patent Publication No. 2004-207172) and a technique in which a crimp terminal and a metal cap are not provided as separate components but rather an electric wire is covered with a part of a strip of terminal to provide a sealed state (Japanese Laid-Open Patent Publication No. 2012-84471).
In the manufacture of a tubular member for crimping an electric wire including an aluminum conductor in a covered state, a method that includes bending a part of a pressed plate into a tubular shape and welding a butted portion or a lapped portion of end portions thereof by laser is advantageous in respect of both shaping and productivity. However, when laser welding is performed, since the weld portion is forcibly dissolved rapidly and then rapidly solidified, a strain is produced in the weld portion. This strain affects adhesion between the crimp portion and an electric wire, and particularly, it is difficult to maintain reliability after aging.
The present disclosure is related to a terminal that can improve adhesion between the tubular crimp portion and an electric wire and reliability can be maintained for a long term, a wire connecting structure and a method of manufacturing a terminal.